In a photomechanical process, it is necessary to obtain high contrast (in particular, 10 or higher than 10 in gamma) characteristics for improving the reproduction of continuous tone images by dot images or the reproduction of line images. Hitherto, for the above-described purpose, a process of using a combination of a light-sensitive material composed of a silver chloride emulsion or a silver chlorobromide emulsion having a high content of silver chloride and a hydroquinone developer (infectious developer) having a very low effective concentration of sulfite ion (usually not more than 0.1 mol/liter) is generally used. However, in the process of using an infectious developer, there is a problem that the developer is very unstable due to the low sulfite ion concentration in the developer and cannot be stably stored over 3 days.
As an improved process for attaining high contrast photographic characteristics using a stable developer, there is a process of using a specific hydrazine compound described in U.S. Pat. No. 4,224,401, etc. According to this process, the existence of a high concentration of sulfite ion in the developer is possible, whereby the developer is protected from aerial oxidation to improve the stability.
Also, in U.S. Pat. No. 4,269,929, it is proposed to add an amine compound to a developer for further improving the above-described high contrast image-forming process using the hydrazine compound and obtaining negative images having high gamma value with a developer having a lower pH value.